The present invention relates generally to shock absorbers. More particularly, it relates to shock absorbers of the type which are mounted to vehicles and which use both an elastomeric shear spring and flow of fluid through a restricted orifice for absorbing shock, structural leveling and energy dissipation. Known shock absorbers of the type described include application Ser. No. 950,949, filed Oct. 13, 1978 now abandoned, in the name of L. Dale Coad.
In the Coad application an expandible and contractible elastomeric bladder for separating a gas chamber from a fluid chamber in a viscous spring damper was provided for varying the spring rate of the damper, calibrating the damper or leveling a load supported thereby.
Dynamic operating characteristics of such dampers are chiefly limited to spring rate, damping response, cyclical active energy consumption and the dissipation percentage thereof. In prior art devices utilizing a single bladder, force-deflection dynamic testing has established that such a device has a sharply variable spring characteristic (spring rate) in compression. In addition, such a device has limitations in damping response and frequency range in compressive motion and in rebound motion reacts as a device with irregular types of damping dependent on load and frequency. Prior art devices have also suffered from a rapidly increasing spring rate as deflection of such a device increases, thereby giving a rough ride to a vehicle containing such devices and incurring high deflection shocks.
The present invention contemplates a new and improved viscous spring damper which exhibits improved operating characteristics over prior viscous spring dampers and which is simple in design, economical to manufacture, readily adaptible to a plurality of energy dissipation uses, easy to install, easy to remove and which provides improved shock absorption and energy dissipation.